High strength multi-component alloy

ABSTRACT

A high strength multi-component alloy contains multi-principal elements and is formulated under a design concept different from the prior art. The multi-component alloy contains Fe, Co, Ni, Cr, Cu and Al as main elements. Each main element of the multi-component alloy is in the range of about 5 to about 35 atom % based on the total number of atoms of the alloy. The multi-component alloy has high strength at high temperature.

BACKGROUND OF THE INVENTION

[0001] 1. Field of Invention

[0002] The present invention relates to a multi-component alloy, andparticularly relates to a multi-principal-element alloy that has highstrength at high temperature.

[0003] 2. Related Art

[0004] An alloy is made by mixing at least one metal element with one ormore metal elements or one or more non-metals. The alloy formed of twokinds of element is called a binary alloy. Similarly, the alloy formedof multiple kinds of element is called a multi-component alloy.Typically, the alloy is based on one or two principal (or main) metalelements. If the alloy is based on Fe, then the alloy can be called aFe-based alloy, which widely includes steel materials such as alloysteel, tool steel and high-speed steel. If the alloy is based on Al,then the alloy is called an Al-based alloy, which is also welldeveloped. Specially, the superalloy has been widely used in variousfields includes Fe-based alloy, Co-based alloy, and Ni-based alloy.Conventionally, the alloy contains more than 40 atom % of the mainelement(s) based on the total number of atoms of the alloy and thebalanced amount of other elements. The above alloying design conceptlimits the freedom of formulation for the alloy and its applications.

[0005] The temperature at which the alloy can be used is a main concernwhen selecting a high temperature alloy. For example, carbon steel orlow-alloy steel is suitable for temperature lower than 370° C. Stainlesssteel is usually used at a temperature lower than 425° C. The strengthof this type of alloy rapidly deteriorates as the temperature increases.Especially when the temperature gets higher than 500° C., the strengthof this type of alloy is almost lower than 200 MPa, which greatly limitsits applications. The superalloy can be used in high temperatureenvironment, for example, at the temperature higher than 540° C. Withincertain ranges of temperature, the strength of the superalloy is notadversely affected as the temperature increases. The common superalloyused in high temperature environment includes Ni-based superalloy andCo-based superlloy. The Ni-based superalloy is usually used for productswhich need high strength at high temperature. The Co-based superalloyexhibits high strength at high temperature of 730-1100° C. Such types ofalloy has more than 400 MPa of yield stress at 800° C. after beingforged. The superalloy is typically based on a single main element suchas Ni or Co, in amount of 45-75 atom %. Secondary elements such aschromium, cobalt, nickel, molybdenum, tungsten, niobium, titanium,aluminum, iron, manganese, silicon, carbon, boron, zirconium andvanadium are optionally added in the alloy to further modify the alloycharacteristics for high temperature use. Such alloys with single mainelement content have been well developed. However, it is hard to furtherimprove their high temperature strength with the currently knowncompositions.

SUMMARY OF THE INVENTION

[0006] In order to produce a multi-component alloy with goodhigh-temperature mechanical properties, the invention provides ahigh-strength alloy that contains multi-principal multiple elements andis formulated under a design concept different from the prior art. Theamount of each main element of the alloy of the invention is in therange of about 5 to 35 atom % based on the total number of atoms of thealloy. The multi-component alloy of the invention has high strength athigh temperature.

[0007] In order to achieve the above and other objectives, themulti-component alloy of the invention contains Fe, Co, Ni, Cr, Cu andAl as main elements. Each main element of the alloy is in the range ofabout 5 to 35 atom % based on the total number of atoms of the alloy. Ithas been experimentally proved that the alloy of the invention has highstrength at high temperature. The multi-component alloy thereforeprovides higher freedom for alloy design. Furthermore, the content ofeach component can be adjusted as desired.

[0008] The invention further provides a high strength multi-componentalloy containing 13-19 atom % Fe, 13-19 atom % Co, 13-19atom % Ni,13-19atom % Cr, 13-19atom % Cu, and 5-35atom % Al, based on the totalnumber of atoms of the alloy. Furthermore, the multi-component alloy canbe produced by the conventional alloy production process and meltingprocess, such as electrical melting, induction melting, arc melting,plasma melting, electron beam melting, powder metallurgy, rapidsolidification, and mechanical alloying in an atmospheric, protective orvacuum environment.

[0009] Further scope of applicability of the present invention willbecome apparent from the detailed description given hereinafter.However, it should be understood that the detailed description andspecific examples, while indicating preferred embodiments of theinvention, are given by way of illustration only, since various changesand modifications within the spirit and scope of the invention willbecome apparent to those skilled in the art from this detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present invention will become more fully understood from thedetailed description given herein below illustration only, and thus arenot limited of the present invention, and wherein:

[0011]FIG. 1 is a graph illustrating the relationship between the yieldstress and the temperature according to examples 1-3 of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0012] The multi-component alloy mainly contains Fe, Co, Ni, Cr, Cu andAl elements. Each of theses elements is in the range of about 5-35atom %based on the total number of atoms of the alloy to impart themulti-component alloy which has excellent high-temperature mechanicalproperties.

[0013] Table 1 shows elements and contents of a multi-component alloyaccording to various examples (e.g. example 1 to example 3) of theinvention. TABLE 1 Content of each main element of the multi-componentalloy (atom %) Alloy No. Fe Co Ni Cr Cu Al Example 1 18.2 18.2 18.2 18.218.2 9 Example 2 16.7 16.7 16.7 16.7 16.7 16.5 Example 3 14.3 14.3 14.314.3 14.3 28.5

[0014] In the example 1, the multi-component alloy contains 18.2 atom %Fe, 18.2 atom % Co, 18.2 atom % Ni, 18.2 atom % Cr, 18.2 atom % Cu and 9atom % Al.

[0015] In the example 2, the multi-component alloy contains 16.7 atom %Fe, 16.7 atom % Co, 16.7 atom % Ni, 16.7 atom % Cr, 16.7 atom % Cu and16.5 atom % Al.

[0016] In the example 3, the multi-component alloy contains 14.3 atom %Fe, 14.3atom % Co, 14.3 atom % Ni, 14.3 atom % Cr, 14.3 atom % Cu and28.5atom % Al.

[0017] About 2000 g of raw material is formulated according to thecompositions shown in Table 1 and melted in a vacuum induction furnace.Then, the melt is poured in a copper mold and solidified to form a castbulk. The cast ingot is cut and machined to produce a plurality ofcylindrical rod of 10 mm in diameter, 15 mm in height.

[0018] Vicker's hardness values for the alloy rod samples are measuredby using Matsuzawa Seiki MV-1 Vicker's hardness tester under theconditions of 5 kg of load, 70 μm/s of loading speed, and 20 seconds ofloading duration. The samples are ground respectively with siliconcarbide sand papers 180#, 240#, 400#, 600#, 800#, 1200# before testing.Mean value of hardness measures taken at 7 different locations iscalculated to estimate Vicker's hardness for each alloy sample. Vicker'shardness measures of the examples 1 to 3 are HV208, HV406 and HV566,respectively.

[0019] The alloy rod samples of examples 1-3 then undergo hightemperature compression in a Gleeble 2000AA dynamic thermal-mechanicalsimulator. 0.2% offset of yield stress is obtained. The high temperaturecompression test is performed by heating the alloy sample to a testtemperature at 10° C./sec and then keep the test temperature for 2minutes to obtain a constant interior temperature. Then, a test underconditions of 10 s⁻¹ of strain rate, and 300-1200° C. of testtemperature is performed. FIG. 1 is a graph illustrating therelationship between the yield stress and the temperature according toexamples 1-3 of the invention. In each of the examples 1-3, only thecontent of aluminum differs. From the results of example 1-3, it isfound that the yield stress increases as the content of the aluminumincreases, and the yield stress at a temperature lower than 800° C. islarger than 400 MPa. Besides, the invention provides a high strengthmulti-component alloy containing 13-19atom % Fe, 13-19atom % Co,13-19atom % Ni, 13-19atom % Cr, 13-19atom % Cu and 5-35 atom % Al.

[0020] The yield stress of the example 1 is not significantly changedwith a variation in temperature between 300 and 800° C. That is, theyield stress is not greatly reduced as the temperature increases. Whenthe test temperature in the example 2 is 900° C., the yield stressobtained is larger than 400 MPa. When the test temperature in theexample 3 is 1100° C., the yield stress is also larger than 400 MPa.From the results shown in FIG. 1, the high strength multi-componentalloy exhibits excellent mechanical performance in high temperatureenvironment, compared to conventional heat-resistant stainless steel andsuperalloy.

[0021] In the following example 4 to example 8, the content of one ofthe main elements is varied while the others are similar. The mainelements and ratios of the multi-component alloy are listed in thefollowing Table 2. TABLE 2 Content of each main component of themulti-component alloy (atom %) Alloy No. Fe Co Ni Cr Cu Al Example 4 918.2 18.2 18.2 18.2 18.2 Example 5 18.2 9 18.2 18.2 18.2 18.2 Example 618.2 18.2 9 18.2 18.2 18.2 Example 7 18.2 18.2 18.2 9 18.2 18.2 Example8 18.2 18.2 18.2 18.2 9 18.2

[0022] In the example 4, the multi-component alloy contains 9 atom % Fe,18.2 atom % Co, 18.2 atom % Ni, 18.2 atom % Cr, 18.2 atom % Cu and 18.2atom % Al.

[0023] In the example 5, the multi-component alloy contains 18.2 atom %Fe, 9 atom % Co, 18.2 atom % Ni, 18.2 atom % Cr, 18.2 atom % Cu and 18.2atom % Al.

[0024] In the example 6, the multi-component alloy contains 18.2 atom %Fe, 18.2 atom % Co, 9 atom % Ni, 18.2 atom % Cr, 18.2 atom % Cu and 18.2atom % Al.

[0025] In the example 7, the multi-component alloy contains 18.2 atom %Fe, 18.2 atom % Co, 18.2 atom % Ni, 9 atom % Cr, 18.2 atom % Cu and 18.2atom % Al.

[0026] In the example 8, the multi-component alloy contains 18.2 atom %Fe, 18.2 atom % Co, 18.2 atom % Ni, 18.2 atom % Cr, 9 atom % Cu and 18.2atom % Al.

[0027] Vicker's hardness values of the multi-component alloys accordingto the examples 4 to 8 are obtained in the same way as in the examples1-3. The results are listed in the following Table 3. TABLE 3 Alloy No.Vicker's hardness Example 4 HV418 Example 5 HV473 Example 6 HV423Example 7 HV367 Example 8 HV458

[0028] Vicker's hardness values of the examples 4 to 8 are higher thanHV208 of the example 1. The multi-component alloy according to theinvention having a considerably wide content range exhibits highhardness.

[0029] Furthermore, under the design concept of the multi-componentalloy according to the invention, no more than 4.5 atom % of secondaryelements other than the main elements, based on the total number ofatoms of the alloy, can be added to the alloy to further modify thecomposition as desired. Examples of secondary elements includemolybdenum, tungsten, niobium, tantalum, scandium, titanium, vanadium,manganese, zirconium, boron, carbon, nitrogen and silicon.

[0030] The following Table 4 shows ingredients of the multi-componentalloy according to the invention and Vicker's hardness values of alloysamples produced from the multi-component alloy. TABLE 4 Vick- Contentof each main component of the Other er's multi-component alloy (atom %)ele- Hard- Alloy No. Fe Co Ni Cr Cu Al ments ness Example 9 17.5 17.517.5 17.5 17.5 8.8 3.5 B HV347 Example 17.5 17.5 17.5 17.5 17.5 8.8 3.5Si HV266 10 Example 17.5 17.5 17.5 17.5 17.5 8.8 3.5 Mo HV220 11 Example18.5 18.5 18.5 18.5 18.5 5.6 1.9 C HV210 12 Example 27.8 13.9 13.9 13.913.9 13.9 2.7 C HV287 13 Example 15.9 15.9 31.8 15.9 8 8 4.5 C HV305 14

[0031] It will be apparent to the person skilled in the art that theinvention as described above may be varied in many ways. Such variationsare not to be regarded as a departure from the spirit and scope of theinvention, and all such modifications as would be obvious to one skilledin the art are intended to be included within the scope of the followingclaims.

What is claimed is:
 1. A high strength multi-component alloy, expressedin terms of atoms based on the total number of atoms of the alloy,comprising: a % Fe, 5≦a≦35; b % Co, 5≦b≦35; c % Ni, 5≦c≦35; d % Cr,5≦d≦35; e % Cu, 5≦e≦35; and f % Al, 5≦f≦35; wherein a+b+c+d+e+f≦100. 2.The high strength multi-component alloy of claim 1, further comprises atleast a secondary element other than Fe, Co, Ni, Cr, Cu and Al, in anamount within the range of 0.01-4.5 atom % based on the total number ofatoms of the alloy.
 3. The high strength multi-component alloy of claim2, wherein the secondary element is selected from the group consistingof molybdenum, tungsten, niobium, tantalum, scandium, titanium,vanadium, manganese, zirconium, boron, carbon, nitrogen and silicon. 4.The high strength multi-component alloy of claim 1, wherein therespective atomic percentages of Fe, Co, Ni, Cr and Cu are 13-19% basedon the total number of atoms of the alloy.
 5. A high strengthmulti-component alloy, expressed in terms of atoms based on the totalnumber of atoms of the allow composition, comprising: a % Fe, 5≦a≦35; b% Co, 5≦b≦25; c % Ni, 5≦c≦35; d % Cr, 5≦d≦25; e % Cu, 5≦e≦25; and f %Al, 5≦f≦35; wherein a+b+c+d+e+f≦100.
 6. The high strengthmulti-component alloy of claim 5, further comprises at least a secondaryelement other than Fe, Co, Ni, Cr, Cu and Al, in an amount within therange of 0.01-4.5 atom % based on the total number of atoms of thealloy.
 7. The high strength multi-component alloy of claim 5, whereinthe secondary element is selected from the group consisting ofmolybdenum, tungsten, niobium, tantalum, scandium, titanium, vanadium,manganese, zirconium, boron, carbon, nitrogen and silicon.